The present invention relates to novel compounds capable of modulating the activity of LXRs, to the process for their manufacture and to pharmaceutical compositions containing them.
Liver X receptors (LXRs) are transcription factors belonging to the superfamily of the nuclear receptors, which also include retinoic acid receptors (RXRs), farnesoid X receptors (FXRs) and peroxisome proliferator-activated receptors (PPARs). On binding to RXRs, LXRs form a heterodimer which attaches itself specifically to the DNA response elements (LXREs), leading to the transactivation of target genes (Genes Dev. 1995; 9: 1033-45).
These receptors are involved in many metabolic pathways and participate particularly in the homeostasis of cholesterol, bile acids, triglycerides and glucose.
Modulation of the activity of these nuclear receptors influences the progression of metabolic disorders such as type II diabetes, dyslipidemia and the development of atherosclerosis.
The LXR/RXR heterodimer can be activated by LXR and/or RXR ligands. Transactivation of the target genes requires the recruitment of co-activators such as Grip-1 (Nature 1996; 383: 728-31).
The two types of LXRs identified hitherto, namely LXRα and LXRβ, have a high degree of similarity in their amino acid sequence, but differ in their tissue distribution. LXRα is strongly expressed in the liver and to a lesser extent in the kidneys, the intestine, the adipose tissue and the spleen. LXRβ is distributed ubiquitously (Gene 2000; 243: 93-103; N.Y. Acad. Sci. 1995; 761: 38-49).
Although LXRs are not activated directly by cholesterol, they are activated by mono-oxidized derivatives of cholesterol (oxysterols), more particularly 22 (R)-hydroxycholesterol, 24 (S)-hydroxycholesterol and 24 (S), 25-epoxycholesterol. These oxysterols are considered to be the physiological ligands of LXRs (Nature 1996; 383: 728-31; J. Biol. Chem. 1997; 272: 3137-40). Also, it has been shown that the oxysterol 5,6,24 (S), 25-diepoxycholesterol is a specific ligand of LXRα, which suggests that it is possible to develop specific ligands of LXRα and/or LXRβ (Proc. Natl. Acad. Sci. USA 1999; 96: 26-71; Endocrinology 2000; 141: 4180-4).
Elsewhere, it has been possible to demonstrate that human plasma contains natural antagonists of LXRα and β (Steroids 2001, 66. 473-479).
Using rat hepatocytes, it has been possible to show that unsaturated fatty acids substantially increase the expression of LXRα without affecting LXRβ (Mol. Endocrinol. 2000; 14: 161-171). Furthermore, activators of PPARα and γ also induce the expression of LXRα in human primary macrophages.
The high concentrations of LXRα in the liver and the identification of endogenous ligands of LXR have suggested that these receptors play an essential role in the metabolism of cholesterol. Under physiological conditions, the homeostasis of cholesterol is maintained via regulation of the pathways of de novo synthesis and catabolism. Via a feedback mechanism involving transcription factors such as SREBP-1 and SREBP-2, the accumulation of sterols in the liver leads to inhibition of the biosynthesis of cholesterol (Cell 1997; 89: 331-40). The excess cholesterol also activates another metabolic pathway, which leads to conversion of the cholesterol to bile acids. Cholesterol is converted to 7α-hydroxycholesterol by an enzyme located in the liver (CYP7A: 7α-hydroxylase) (J. Biol. Chem. 1997; 272: 313-40).
The involvement of LXR in the synthesis of bile acids, and hence in the regulation of cholesterol homeostasis, has been demonstrated by means of LXRα-deficient mice, which, when subjected to a fatty diet, accumulate large amounts of cholesterol esters in the liver (Cell 1998; 93: 693-704). LXRβ-deficient mice have the same physiological resistance as normal mice to a fat-enriched diet. The expression of unchanged LXRβ in LXR-deficient mice tends to demonstrate that LXRβ on its own is incapable of substantially increasing cholesterol metabolism (J. Clin. Invest. 2001; 107: 565-573).
LXRs expressed in macrophages also play an important role in the regulation of certain macrophage functions. More particularly, they are involved in the control of reverse cholesterol transport, which enables the excess cholesterol to be exported from the peripheral tissues to the liver. The cholesterol is taken in charge by pre-bHDLs via apoA1 and ABCA1 for transportation to the liver, where it is catabolized to bile acids and then eliminated.
ABCA1 is a member of the superfamily of transport proteins (ATP-binding cassette), whose importance is illustrated by the fact that a mutation in the ABCA1 gene is responsible for Tangier disease (Nat. Genet. 1999; 22: 336-45).
The expression of ABCA1 and the efflux of cholesterol are induced by loading of the human macrophages with cholesterol and activation of the LXRs (Biochem. Biophys. Res. Comm. 1999; 257: 29-33). It has subsequently also been demonstrated that the expression of ABCG1, ABCG5 and ABCG8, other members of the family of ABC-type transporters, in the intestine is also regulated by the RXR/LXR heterodimer (J. Biol. Chem. 2000; 275: 14700-14707; Proc. Natl. Acad. Sci. USA 2000; 97: 817-22; J. Biol. Chem. 2002; 277: 18793-18800; Proc. Natl. Acad. Sci. USA 2002; 99: 16237-16242).
It has also been shown that agonistic ligands of LXR reduce atheromatous lesions in two different mouse models (ApoE−/− mice and LDLR−/− mice) (Proc. Natl. Acad. Sci. USA 2002; 99: 7604-7609; FEBS Letters 2003; 536: 6-11). These results suggest that LXR ligands can constitute therapeutic agents for the treatment of atherosclerosis.
Finally, it is known that macrophages play an important role in inflammation, particularly in the pathogenesis of atherosclerosis. It has been shown that the activation of LXRs inhibits the expression of the genes involved in inflammation in macrophages (Nature Medicine 2003; 9: 213-219). In vitro the expression of mediators such as nitric oxide synthase, cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6) is inhibited. In vivo LXR agonists reduce inflammation in a dermatitis model and inhibit the expression of the genes involved in the inflammation of atheromatous mouse aortas.
Because the homeostasis of cholesterol also seems to play an essential role in the function of the central nervous system and the mechanisms of neurodegeneration, the expression of ABCA1 has also been studied in cultures of primary neurons, astrocytes and microglia isolated from rat embryo brains. The results of these studies show that activation of the LXRs leads to a decrease in the secretion of amyloid β and consequently to a reduction in amyloid deposits in the brain. These studies suggest that activation of the LXRs may constitute a novel approach to the treatment of Alzheimer's disease (J. Biol. Chem. 2003; 275 (15): 13244-13256, J. Biol. Chem. 2003; 278 (30): 27688-27694).
LXRs are also involved in regulating the expression of apolipoprotein E (ApoE). This protein is greatly involved in the hepatic clearance of lipoproteins and favors the efflux of cholesterol from lipid-rich macrophages. It has been demonstrated that the activation of LXRs leads to an increase in the expression of ApoE via an LXR response element (LXRE) situated in the sequence of the ApoE promoter (Proc. Natl. Acad. Sci. USA 2001; 98: 507-512).
The activation of LXRs would also favor cholesterol reverse transport via modulation of the expression of CETP (cholesterol ester transfer protein), which is involved in the transfer of esterified cholesterol from the HDLs to the triglyceride-rich lipoproteins eliminated by the liver (J. Clin. Invest. 2000; 105: 513-520).
In summary, the activation of LXRs leads to an increase in the expression of numerous genes that favor the elimination of excess cholesterol from the peripheral tissues. In macrophages loaded with cholesterol, the activation of LXRs increases the expression of ABCA1, ABCG1, ABCG5, ABCG8 and ApoE, causing an increase in the efflux of cholesterol from the macrophages to the liver, where it is excreted in the form of bile acids. Induction of the expression of CETP and CYP7A in the liver leads respectively to an increase in the hepatic clearance of cholesterol esters from the HDLs and to the catabolism of cholesterol.
Elsewhere, it has also been demonstrated that LXRs play an important role in the metabolism of glucose. The treatment of diabetic rodents with an LXR agonist leads to a drastic decrease in the plasma glucose levels. Particularly in the insulin-resistant Zucker (fa/fa) rat, the activation of LXRs inhibits the expression of the genes involved in gluconeogenesis, including more particularly phosphoenolpyruvate carboxykinase (PEPCK) (J. Biol. Chem. 2003, 278 (2): 1131-1136).
Also, it has been shown that an LXR agonist increases glucose tolerance in a mouse model of insulin resistance and obesity (Proc. Natl. Acad. Sci. USA 2003; 100: 5419-5424). Gene expression analysis demonstrates regulation of the genes involved in glucose metabolism in the liver:                decrease in the expression of peroxisome proliferator-activated receptor coactivator-1α (PGC-1), phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase;        induction of the expression of glucokinase, which favors the utilization of hepatic glucose.        
A transcriptional induction of insulin-sensitive glucose transporter (GLUT4) in the adipose tissue has also been demonstrated.
These results emphasize the importance of LXRs in the coordination of glucose metabolism.
It is also known that LXRs participate in inflammation regulation processes (Nature Medicine 2003, 9: 213-219).
Compounds that modulate LXR activity are known in the state of the art, especially from the documents WO 03/090869, WO 03/90746, WO 03/082192 or WO 03/082802, or the documents WO 03/043985 and WO 04/005253, which describe compounds of the benzenesulfonamide type which are PPAR agonists.
In this context there is a significant interest in finding novel compounds which modulate LXR activity and which would be useful in the treatment of certain pathological conditions such as cardiovascular disease, hypercholesterolemia, dyslipidemia, myocardial infarction, atherosclerosis, diabetes, obesity, inflammation and neurodegenerative disease.
The present invention is based precisely on the discovery of novel compounds that modulate LXR activity.
Thus, according to a first feature, the aim of the present invention is to protect, as a novel industrial product, a sulfonylindoline compound, wherein it is selected from:
i) the compounds of the formula
in which:                R1 is a hydrogen atom, a halogen, a C1-C4 alkyl group, a C1-C4 alkoxy group, a trifluoromethyl group or a totally or partially halogenated methoxy group,        R2 is a hydrogen atom, a halogen, a C1-C4 alkyl group or a trifluoromethyl group,        R3 is a hydrogen atom, a halogen, a C1-C4 alkyl group or a trifluoromethyl group, with the proviso that R1, R2 and R3 are not simultaneously a hydrogen atom,        R4 is a hydrogen atom or a C1-C4 alkoxy group,        Y is a linear or branched C1-C8 alkylene group optionally substituted by a trifluoromethyl group or by a phenyl ring, or containing a cyclized part having 3 to 6 carbon atoms, or is a group —(CH2)n—W—,        W is an oxygen atom, a group —NH— or a sulfur atom,        n is 2, 3 or 4,        Z is an optionally partially halogenated C1-C4 alkyl group, trifluoromethyl, —CORa, —CH2—N(R)2, or an aromatic, heteroaromatic or heterocyclic ring selected from phenyl, pyrrolidinyl, pyrrolidinylone, imidazolyl, pyridinyl, pyridinyl oxide, piperidinyl, piperazinyl, pyridazinyl, morpholinyl and indolinylone groups, and optionally substituted by one, two or three identical or different substituents selected from a halogen, a C1-C4 alkyl group, C1-C4 alkoxy, trifluoromethyl, nitro, N(R)2, —CH2—N(R)2, —O—(CH2)n—N(R)2, hydroxyl, cyano, C2-C3 cyanoalkyl, 5-oxo-1,2,4-oxadiazolidinyl and a group of the formula —X—[C(R)2]p—CORa,        X is a single bond, an oxygen atom, —O—CH2—, a sulfur atom, a group —NR— or a 1,1-cyclopropylene group,        Ra is OR or N(R)2,        R is a hydrogen atom or a C1-C4 alkyl group, and        p is equal to 0, 1, 2, 3 or 4; andii) the pharmaceutically acceptable salts of said compounds of formula (I).        
According to a second feature, the invention relates to the above-mentioned compounds for their use as pharmacologically active substances.
In particular, the invention relates to the use of at least one compound of formula (I) or one of its pharmaceutically acceptable salts as active principles for the preparation of a drug to be used in therapeutics, especially for combating hypercholesterolemia, dyslipidemia, hypertriglyceridemia, obesity and the cardiovascular diseases which are the consequence of a serum lipoprotein imbalance. The compounds according to the invention are also useful as active principles of drugs for the prevention or treatment of atherosclerosis, myocardial infarction, certain inflammatory diseases, e.g. dermatitis, and neurodegeneration, e.g. Alzheimer's disease. The compounds according to the invention are also useful as active principles of drugs for the treatment of diabetes and hyperglycemia.